Safe or steel-vault wall.



UNITED STATES PATENT OFFICE.

rmfiz WILHELM SCHILLING, or ESSEN-ON-THE-RUI-IR, GERMANY, AssIGNoR 'roFRIED. KRUPP AKTIENGESELLSCHAFT, or ESSEN-ON-THE-RUHR, GERMANY.

SAFE OR STEEL-VAULT WALL.

No Drawing.

' To all whom it may concern:

' through by the blow-pipe flame of oXyhy-,

composition of the steel'tq drogen gas, acetylene, et cetera.

It is old to employ a special kind of cast iron for the-production of'such walls. However in that case it is necessary to take into accountthe disadvantage of'brittlenessincident to all cast irons.

The object of this invention is to remove this disadvantage. This objectis attained by using an iron-carbon alloy having the which is added asufficient amount of chromium.

The smaller the carbon content is the greater must the chromium contentbe. In alloys which, aside from the chromium, contain no other additionaffecting the resistance of the alloy against melting the mimimumcontent of chromium must be about 6.5% for 0.7% (1, about 5.5% for 1.0%C., about 4.3% for 1.4% (1., about 4.0% for 2.0% o.

Generally the necessary minimum content of chromium amounts to if Cindicates the percentage o'f carbon.

Under certain circumstances it is,preferable to add tungsten (W) orsilicon besides Specification of Letters Patent.

for instance, by an alloy which contains.

more than 1% C, 9% Cr and 3% W.

Having thus described the invention what is claimed and desired to besecured by Letters Patent is:

1. A safe or steel-vault wall made from an iron-carbon alloy having thecomposition Patented May 14, 1912. Application filed April 3, 1910.Serial No. 553,810.

of steel and containing such a high amount of chromium, that it cannotbe' melted through by the blow-pipe flame of oxyhy drogen gas.-

2. A safe or steel-vault wall made from an iron-carbon alloy having thecomposi tion of steel and containing such a high' amount of chromium andtungsten, that it cannot be melted through by the blow-pipe flame ofoxyhydrogen gas.

3. A safe or steel-vault wall, made from an iron-carbon alloy having thecomposition of steel and containing more than 1% carbon, more than 9%chromium and more than 3% tungsten. f

The foregoing specification signed at Barmcn, Germany, this 22nd day ofMarch, 1910. 1

FRANZ WILHELM SGHIL'LING. [L. 8.]

